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|What is a Skiving Machine?
A skiving machine is used in an industrial setting to cut or shave the edge of a moving strip of material into a desired shape or to create cross-sections of stock. Also called scarfing machines, skiving machines are commonly used in applications where uniform sizes and shapes are needed but are not obtainable using other manufacturing processes, such as cold rolling. Although skiving machines are most commonly used in the process of metalworking, they also see a significant amount of use in the edge shaping of leather and similar materials.
The process of using a skiving machine is called skiving or skivetek. Using a tungsten carbide blade, the skiving machine can cut metal and other materials with greater precision than many machine tools. Advances in the technology used in skiving machine parts has made these machine tools easier to use by introducing a floating blade system that moves both the blade and the material to achieve uniform sized cuts, rather than the older style machines that required careful adjustments of the stock to the blade to achieve the same effect.
Advances in the technology used in modern skiving processes have also made it possible to plane metal and other materials at slower speeds than were attainable in the past. Using vibration to simulate an increase in speed of the moving stock, the modern skiving machine is able to cut materials that would not have been possible in early machine tool shops. This ability to cut metal at a slower speed makes it possible to utilize the skiving machine in conjunction with low-speed welding on assembly lines.
Skiving machines are commonly used in the manufacture of automobile parts, including seat belt springs and hose clamps. These machines are also used to bevel the edges of metals used in the manufacture of pipes and tubing. This beveling allows the tubing product to be seam-welded in a way that avoids pinholes in the final product.
The electronic supply industry uses the skiving machine to create highly effective heat sinks. The skiving machine's cutting abilities are why these heat sinks can be made from a single piece of metal, thus allowing the heat sinks to transfer and dissipate heat more effectively. The process of skiving leaves the fins of the heat sink with a roughened texture that creates a greater surface area and further enhances heat dispersal.
Skived Heat Sinks
Skived copper heat sinks offer the maximum heat dissipation in applications that have high airflow and small space. The thermal conductivity of copper (~400 W/m-K) is the highest among all the commercial metals, and the skiving technology allows the heat sinks to have very thin fins, high aspect ratio and high fin density. Because the fins are an integral part of the base, skived copper heat sinks provide the best possible thermal conductivity between the fins and the base. When optimized to specific applications, skived copper heat sinks offer outstanding performance over any other thermal solutions within the small space. In some applications, the skiving technology is also the most cost-effective and reliable method of producing heat sinks that meet high thermal demands.Skived heat sinks are manufactured by peeling fins from a bar of solid copper or aluminum, using a sharp and accurately controlled blade tool. The tool shaves a small thickness of the material, lifts it up and bends it vertically to form the fin. The final heat sink can be machined using normal fabrication techniques, such as CNC machining. Skived heat sinks require minimal tooling cost, which makes it a cost effective solution. Skived heat sinks can also be customized with embedded heat pipes to further improve performance.
Features and Benefits
Very thin fins and very high fin density
Maximum heat dissipation under forced convection (with high airflow)
No interface joint (or thermal resistance) between the fins and base
Very high aspect ratio (up to 50)
Minimal tooling cost
Short lead time
Can have embedded heat pipes to further boost performance
Anti-oxidation surface treatment helps extend serving time
Applications of Skived Heat Sinks
Skived copper heat sinks deliver maximum heat dissipation in applications with limited space and high levels of ventilation. They are a cost effective solution when considering the low tooling cost and the optimized fin surface area.
Skived fin heat sinks are commonly found in the following applications:
Computers and electronic components
Industrial equipment and components
Lighting lamps and household appliances industry
The following parameters are the limitation and/or recommended values for skived heat sinks with high quality and low cost.
Material: Copper (C11000) or Aluminum (6063/1060)
Maximum width: unlimited
Maximum fin length: 500 mm (20″)
Maximum fin height: 100 mm (4”)
Recommended fin height: <50 mm (2”)
Recommended thickness for aluminum fins: 0.2-1.2 mm (0.008-0.047”)
Recommended thickness for copper fins: 0.1-0.6 mm (0.004-0.024”)
Minimum fin spacing (gap): 0.1 mm (0.004”)
Maximum fin spacing (gap): 8.0 mm (0.31”)
Hydraulic Hose Fittings: Skived vs Non-Skived
Special attention must be given to hose assemblies. The two preparation options to choose from are skiving or non-skiving a hydraulic hose.
SKIVING Skiving a hydraulic hose is the process of using special equipment and tooling to shave a predetermined depth of the OD and ID of the hose. Some medium pressure hose fittings require only external skiving (or single skive) in order for the ferrule and hose fitting to mate correctly.
Higher pressure hose applications may require internal and external skiving. Skiving a hydraulic hose ensures a metal to metal connection between the hose fitting and hose, resulting in a highly reliable connection.
Skiving lets the ferrule of the hose fitting assembly bite into the wire braiding of the hose instead of just crimping to the outside diameter (OD) of the hose cover. If the hose is not skived the thread of the ferrule is forced into the hose cover, biting into the rubber, which could result in a less reliable connection. Once the assembly has been set, it is essential to correctly crimp the fitting onto the hose using the hose fitting manufacturers’ crimp specifications. Look for fitting manufacturers that can provide crimp specifications for multiple hose manufacturers. If the fitting manufacturer does not provide the crimp specs for a specific hose the installer must make an adjustment. In these cases it is critical that high pressure hoses are pressure tested to ensure the installation is accurate and secure.
NON SKIVING Non-skiving is when the hose and fitting connection is designed ready to assemble without the skiving process, with no removal material from the hose. If the hose is not skived the thread of the ferrule is forced into the hose cover, biting into the rubber, which could result in a less reliable connection.
Understanding Heat Sinks: Functions, Types, & More
Heat sinks are one of the most common forms of thermal management in technology, machinery, and even in natural systems. These components are so ubiquitous that they're easy to overlook, even by those who are familiar with the technology. We'll address the basic working principles involved in heat sinks, introduce active and passive heat sink configurations, and discuss how some users implement heat sinks in their applications.
What is a Heat Sink?
A heat sink is a component that increases the heat flow away from a hot device. It accomplishes this task by increasing the device's working surface area and the amount of low-temperature fluid that moves across its enlarged surface area. Based on each device's configuration, we find a multitude of heat sink aesthetics, design, and ultimate capabilities. You can see a straight fin heat sink in the image at the top of this article and a flared fin heat sink in the image below. Each heat sink is valuable in applications that may have varying:
How Does a Heat Sink Work?
A heat sink works by moving heat away from a critical component. Nearly all heat sinks accomplish this task in four basic steps:
1. The source generates heat. This source may be any system that creates heat and requires the removal of said heat to function correctly, such as:
2. Heat transfers away from the source. Heat pipes can also aid in this process, but we'll cover those components separately. In direct heat sink-contact applications, heat moves into the heat sink and away from the source via natural conduction. The heat sink material's thermal conductivity directly impacts this process. That's why high thermal conductivity materials such as copper and aluminum are most common in the construction of heat sinks.
3. Heat distributes throughout the heat sink. Heat will naturally travel through the heat sink via natural conduction moving across the thermal gradient from a high temperature to a low-temperature environment. This ultimately means that the heat sink's thermal profile will not be consistent. As such, heat sinks will often be hotter towards the source and cooler towards the sink's extremities.
4. Heat moves away from the heat sink. This process relies on the heat sink's temperature gradient and its working fluid―most commonly air or a non-electrically-conductive liquid. The working fluid passes across the surface of the warm heat sink and utilizes thermal diffusion and convection to remove heat away from the surface and into the ambient environment. This stage relies on, yet again, a temperature gradient to remove heat from the heat sink. Therefore, if the ambient temperature is not cooler than the heat sink, no convection and subsequent heat removal will occur. This step is also where the total surface area of the heat sink becomes most advantageous. A large surface area provides an increased area for thermal diffusion and convection to occur.
A Copper Heatsink is sometimes used as a heatsink as it is a good conductor of heat. This can be observed if you heat one end of a piece of copper, the other end will quickly reach the same temperature. Copper is used in many heating applications because it doesn't corrode and has a high melting point.
The properties that make a copper heatsink popular include:
Good thermal and electrical conductivity
Density ~ 0.321 lb/in3
Tensile strength of ~ 310 MPa
Easy to recycle
Copper heatsink vs. Aluminum heatsink
Copper is an excellent conductor of heat and Radian uses Cu1100 which has a thermal conductivity of ~ 380W/m-K. Despite the excellent thermal properties of a copper heatsinks, aluminum heatsinks are typically used as they weigh approximately half as much as a copper conductor having the same conductivity, and are also less expensive. Although it is possible to machine a copper heatsink this can be fairly inefficient as the tools blunt fairly quickly. Typical manufacturing is by either the forged or skiving process that allow the copper heatsink to made from a single block. Another manufacturing process that is used especially with vapor chambers is the use of stamped copper fins that are soldered or epoxied onto the base. Many of our customers also add an anti-oxidation coating, or nickel plate to maintain the look of the copper heatsinks as they can tarnish over time.
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